Nanoparticles Comprising Silica Particles Coated with β-Cyclodextrin
Nanoparticles have shown great potential as water-purification catalysts and redox active media for the treatment of organic and inorganic pollutants (Savage et al., Nanomaterials and water purification: opportunities and challenges. J. Nano. Res. 7: 331-342 (2005)). The property of cyclodextrins to form inclusion complexes with various molecules through host-guest interactions (Caliman et al. Clean 37(4-5), 277-303 (2009)) has made them useful compounds for the removal of a number of contaminants from water and wastewater (Yamasaki et al. J Chem Technol Biotechnol 81:1271-1276 (2006), Mhlanga et al. J Chem Technol Biotechnol 82:382-388 (2007), Yamasaki et al. J Chem Technol Biotechnol 83:991-997 (2008), Zhao et al. J Incl Phenom Macrocyl Chem (2009) 63: 195-201). The formation of inclusion complexes with bisphenol A (BPA) has been reported in solution phase (Liu et al. Carbohydrate Research 343(14):2439-2442 (2008)) and in solid phase by using β-cyclodextrin-polymer (β-CD-polymer) (Wang et al. Sensors and Actuators B 114:565-572 (2006)). The commonly available different types of cyclodextrins are α-cyclodextrin, β-cyclodextrin (β-CD) and γ-cyclodextrin which consist of six, seven and eight α-1,4 linked D(C)-glucopyranose units, respectively (Crini, G. Prog. Polym. Sci. 30 38-70 (2005)). The presence of hydroxyl groups at position 2, 3, and 6 in the glucose unit can be used for the structural modifications of cyclodextrins (Khan et al. Chem. Rev. 98, 1977-1996 (1998)) in order to obtain insoluble derivatives of cyclodextrins (Sugiura et al. Bulletin of the Chemical Socitey of Japan 62(5):1643-1651 (1989), Crini, G. Bioresource Technology 90(2):193-198 (2003), Girek et al. Carbohydrate Polymers 59(2):211-215 (2005), Yamasaki et al. J Chem Technol Biotechnol 83:991-997 (2008)) and to immobilize them onto inorganic supports like silica (Armstrong, D. W. U.S. Pat. No. 4,539,399 (1985), Crini et al. Chromatographia 40(5-6):296-302 (1995), Phan et al. Physical Chemistry Chemical Physics 1(22):5189-5195 (1999), Crini et al. Chromatographia 50 (11-12):661-669 (1999), Morcellet et al. Journal of Inclusion Phenomena and Macrocyclic Chemistry 38 (1-4): 345-359 (2000), Phan et al. Reactive & Functional Polymers 52:117-125 (2002), Carbonnier et al. E-Polymers, article no. 004 (2003), Ponchel et al. Microporous and Mesoporous Materials 75(3):261-272 (2004), Saikia et al. Colloids and Surfaces A: Physicochemical and Engineering Aspects 329(3):177-183 (2008)). The chemically bonded organic-inorganic particles combine the advantageous properties of both inorganic support (excellent mechanical strength) and bonded organic compounds (high efficiency, reproducibility and selectivity) (Carbonnier et al. J. of Appl. Polym. Sci. 90:1419-1426 (2004)).